Impulse generator for use with phosphor energizable lamps

ABSTRACT

An impulse generator for use with phosphor energizable lamps, e.g. gaseous discharge lamps and electroluminescent lamps, and which eliminates the need of a conventional ballast and starting mechanism. The impulse generator includes a pair of terminals which are adapted to be connected to a conventional source of alternating electrical current with a diode rectifying bridge for rectifying the electrical current. A solid-state circuit switching element is connected to the rectifier and operates in conjunction with a timing means including a resistive capacitive network. Moreover, the solid-state switching element is connected to a primary coil which is coupled to a secondary coil. The secondary coil includes terminals for connection to the lamp. The circuit is operable to generate pulses in a sequence and at time intervals sufficient to maintain energization of the lamp. Thus, the pulses transmitted to the lamp will maintain ignition of the lamp, such that the pulses are applied to the lamp prior to termination of an electric discharge in the lamp. In one of the preferred aspects, the primary and secondary coils form part of a core transformer with the housing sections being separated to create a gap therebetween. In another aspect, the transformer includes an electrically non-conductive spool which holds the windings and with an electrically conductive core located within the non-conductive spool.

RELATED APPLICATION

This application is a continuation of application Ser. No. 857,220,filed Dec. 5, 1977 for "IMPULSE GENERATOR FOR USE WITH PHOSPHORENERGIZABLE LAMPS", now U.S. Pat. No. 4,129,805.

BACKGROUND OF THE INVENTION

1. Purpose of the invention

This invention relates to certain new and useful improvements in impulsegenerators and method of use therefor, and, more particularly, toimpulse generators in connection with phosphor excitable lamps forenergizing the lamp.

2. Brief Description of the Prior Art

For many years, phosphor excitable lamps have been used, including thewell-known fluorescent lamp, and which have replaced the conventionalincandescent lamp in many applications. These phosphor excitable lampsgenerally operate on the principle of generating ultraviolet radiationand converting the ultraviolet radiation to visible light by energizingthe phosphor coating and hence exciting the phosphors generated by thephosphor coating. Phosphor excitable lamps include, for example, thegaseous discharge lamp and the electroluminescent lamp.

The gaseous discharge lamp, which includes the so-called fluorescentlamp, operates on a principle which makes use of ultraviolet energygenerated by a mercury vapor in an inert gas and which activates acoating of a fluorescent material, often referred to as a phosphor, onthe inner surface of the glass tube. The phosphor acts as a transformerconverting the ultraviolet radiation into visible light.

In most conventional fluorescent lamps and similar gas discharge lamps,the lamp includes a hot cathode located on the interior thereof andconnected to terminals on the exterior of the lamp. In theelectroluminescent lamp, a capacitive effect is achieved with a phosphorcoating on a transparent sheet and with a second electrode beingcomprised of an aluminum or similar metal sheet. These lamps areoperable in conjunction with a number of conventionally known ballasts.The ballast generally is a series reactor transformer and includes alarge number of windings. Thus, the ballast acts as an inductive deviceto increase the voltage for igniting the phosphor excitable lamp. Theballast primarily serves to both ignite the lamp and to also limit thecurrent to the lamp. Immediately after the lamp is ignited, theimpedance of the lamp drops to an almost zero level and, hence, it isnecessary to limit the current after ignition in order to avoidburning-up the lamp. The inductive reactance in the conventional ballastoperates to limit the current after ignition of the lamp.

There are many disadvantages of the conventional ballast system used inconnection with phosphor lamps. One of the disadvantages lies in theweight and size factor of the conventional ballast. Due to the heavytransformer, provision must be made in each conventional lamp fixture inorder to mount and support the weight of the ballast. Moreover, if theyare used for any excessive period of time, the ballast may heat up andmay tend to burn out and require replacement thereof.

In addition to the above, the transformer core in the ballast will tendto vibrate and generate a hum in the audible frequency spectrum. Whilethis hum may not have a great amplitude, it is, nevertheless,distracting and uncomfortable to an individual in proximity to the lightsource. In addition to the above problems, the vibration of the core inthe ballast would often tend to create a flicker in the light. While theflicker may occur at a high frequency, it is nevertheless oftentimesvisible and apparent to the observer.

Another disadvantage of the conventional ballast is that largecapacitors are oftentimes required to correct the power factor and phasedisplacement. These capacitors are relatively expensive due to theirsize and thus substantially increase the overall cost of the ballast.Even moreso, the use of an inductive device of this type often generatesa significant amount of heat and, in many cases, where the lamp is notmounted in an environment where air flow can dissipate the heat, othermeans must be employed to dissipate the heat generated by the ballast.The conventional ballast also tends to generate undesirable radiofrequency signals which may interfere with RF operated equipment.

One of the primary disadvantages of the conventional ballasts, at leastin present energy shortage times, is that the ballast requires a verysubstantial amount of current in order to maintain energization of thelamp. After the lamp has been ignited, a continuing current source isapplied to the two electrodes of the lamp in order to maintainenergization thereof. However, it has been found to maintainenergization thereof. However, it has been found in the presentinvention that it is possible to cause ignition and maintainenergization of the lamp with reduced energy applied to the lamp whencompared to conventional prior art phosphor excitable lamps.

OBJECTS OF THE INVENTION

It is, therefore, the primary object of the present invention to providean impulse generator of the type used with phosphor excitable lamps andwhich is capable of pulsing a phosphor excitable lamp to maintain arelatively constant light output therefrom.

It is another object of the present invention to provide an impulsegenerator of the type stated which significantly lowers powerrequirements for maintaining light emission from a phosphor excitablelamp.

It is a further object of the present invention to provide an impulsegenerator of the type which generates pulses in a sequence and at timeintervals sufficient to maintain energization of the lamp and which doesnot require large capacitors for power factor corrections and phasedisplacement.

It is an additional object of the present invention to provide a systemof a phosphor excitable lamp and an impulse generator for use therewithand which system operates on relatively low power requirements andeliminates the need for ballast and/or a starting mechanism.

It is another salient object of the present invention to provide amethod for igniting and controlling the current flow to a phosphorexcitable lamp by use of an impulse generator which generates pulses ina sequence and at a proper interval to cause ignition of and maintainenergization and phosphor excitation at the lamp.

With the above and other objects in view, my invention resides in thenovel features of form, construction, arrangement and combination ofparts presently described and pointed out in the claims.

GENERAL DESCRIPTION OF THE DISCLOSURE

The impulse generator is designed for use with phosphor excitable lamps,e.g. gaseous discharge lamps, such as, for example the known fluorescentlamps and the relatively new electroluminescent lamps. The impulsegenerator is designed to ignite and control current flow to such lamps.The generator of the present invention in its broad aspect includes apulse generating means for generating pulses of a magnitude to energizethe lamps and a means to control timing of the pulses as applied to thephosphor excitable lamps.

The present invention is operable with generally all forms of phosphorexcitable lamps, that is lamps which operate on the principle ofgenerating ultraviolet light and excitation with phosphors to producelight in the visible spectrum. Thus the impulse generator is operablewith gaseous discharge lamps including the fluorescent lamp andelectroluminescent lamps often referred to as the EL lamps. These lampsare also characterized by their frequency and voltage dependencecharacteristics.

The impulse generator includes the means for generating impulses whichcomprises at least an NPN transistor operable in conjunction with thepulse control timing means or so-called pulse control triggering means.In this case, the pulse control triggering means is a resistive networkcomprising a resistor and a capacitor connected in series and alsoconnected across the base of the transistor. The pulse generating meansincludes a first coil or primary coil which is connected to thecollector of the transistor and is often referred to as a collectorcoil. The primary coil operates in conjunction with a pair of secondarycoils which are electromagnetically coupled to the primary coil. Theterminals of the secondary coils are thereupon connected to the oppositeelectrodes on the phosphor excitable lamp.

The emitter of the transistor is also connected through a third coil oradditional primary coil to the resistive capacitive network, and whichserves as a feedback coil. Moreover, the pulse generating means may beconnected directly by a conductor to one of the terminals on the lamp.

The primary and secondary coils preferably form part of a coretransformer. In this case, the core transformer comprises a central corewith the primary and secondary coils being wound upon the central core.A pair of housing sections is disposed over the core and the coils tosubstantially enclose the core and the coils. The housing sections arespaced apart from each other by a gap. The size of the gap is determinedin order to maintain the life of the transistor.

In another embodiment of the invention, the transformer, which operatesas a type of auto-transformer, is constructed so that the outer housingis eliminated. In this case, the coils are wound on an electricallynonconductive tubular spool with a conductive core disposed within thespool.

One of the aspects of the present invention is that the pulse controltiming means is designed to cause generation of pulses in a sequence andat a proper interval to cause and maintain energization of the lamp, sothat there is no termination of an electric discharge in the gaseousdischarge lamp. In this way, the lamp is consistently energized bypulses designed to ignite the lamp and then permit the lamp to maintainthe phosphor excitation. Thus, the pulses provided on a basic and aretimed so that the lamp will always maintain a light output. Moreover,less current is required and this results in a substantial energysavings.

BRIEF DESCRIPTION OF THE DRAWINGS

Having thus described by invention in general terms, reference will nowbe made to the accompanying drawings in which:

FIG. 1 is a schematic view of a circuit which forms part of the impulsegenerator of the present invention and showing a pair of gaseousdischarge lamps connected thereto;

FIG. 2 is a fragmentary side elevational view, partially broken away andin section, and showing a portion of a conventional gaseous dischargelamp;

FIG. 3 is a schematic side elevational view showing a conventionalelectroluminescent lamp;

FIG. 4A is a schematic view of AC power input into the impulse generatorof FIG. 1 and showing current and voltage relationship;

FIG. 4B is a schematic view of output pulses which are generated by theimpulse generator of FIG. 1;

FIG. 5 is a side elevational view of a core transformer forming part ofthe impulse generator of the present invention;

FIG. 6 is an end elevational view taken along line 6--6 of FIG. 5;

FIG. 7 is a vertical sectional view taken along line 7--7 of FIG. 6; and

FIG. 8 is a side elevational view partially in section showing amodified form of core transformer which may be used with the impulsegenerator of the present invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Referring now in more detail and by reference characters to the drawingswhich illustrate a preferred embodiment of the present invention, Adesignates an electrical circuit forming part of the impulse generatorof the present invention. In this case, the impulse generator A is shownas being connected to a pair of gaseous discharge lamps designated as L₁and L₂.

The gaseous discharge lamps are of a conventional construction, and oneof such lamps L₁ is more fully illustrated in FIG. 2 of the drawings.The lamp comprises a bulb 10, which is shown as having a straight glasstube, although the tube could adopt other shapes, as for example, acircular shape or the like. One end of the tube 10 is provided with anon-conductive base 12 having a plurality (two as shown) of electricalterminals 14. These terminals which are often referred to as "base pins"are connected to lead-in wires 16 located internally within the tube andthe lead-in wires are located in a so-called "stem press" 18 constructedof a material to assure the same coefficient expansion as the glass tube10. The lead-in wires 16 are connected to a hot cathode 19 which isdesigned to ignite a gas in the tube as hereinafter described. The hotcathode is coated with an emissive material which emits electrons and isusually made of a coil, e.g. a simple coil tungsten wire. It should beunderstood that a pair of similar hot cathodes and related structurewould be included at each end of the glass tube 10.

The inside of the bulb or tube 10 is provided with a phosphor coatingwhich transforms ultraviolet radiation into the visible light. The colorof the light often depends on the composition of the phosphor. A minuteamount of mercury is also located in the bulb to furnish the mercuryvapor for purposes of ignition. In addition, an inert gas, such asargon, krypton and the like, may be used.

The coating on the hot cathode is generally formed of an emissivematerial such as barium, strontium, calcium oxide and the like, andwhich emits electrons when heated to an operating temperature of about950° C. After the cathode has been heated to the proper temperature,thermionic emission will occur. The emitted electrons, upon collision,will release ultraviolet radiation which is converted into visible lightby the phosphors.

FIG. 3 illustrates in schematic side elevational view, a form ofelectroluminescent lamp M which can be used in combination with theimpulse generator of the present invention. The lamp M is comprised of aplastic plate 20 which is translucent and preferably transparent in itsconstruction. Applied to one surface of the plate 20 is a phosphorcoating 21 and disposed against the phosphor coating 21 is a metal sheetsuch as an aluminum sheet 22. Conductors 23 are attached to the coating21 and the metal sheet 22. These conductors are adapted for connectionto a suitable source of current through a ballast, and in the case ofthe present invention would be connected to inputs of the impulsegenerator.

The electroluminescent lamp M operates on essentially the same principleas the gaseous discharge lamp. In this case the phosphors are notlocated in a tube or bulb. However, the electroluminescent lamp operateswith a very high frequency creating a capacitive effect across thephosphor coating 21 and the metal sheet 22, with the phosphorsconverting the ultraviolet radiation into visible light radiation.Inasmuch as both lamps operate on similar principles, insofar as theimpulse generator of the present invention is concerned, the operationof the impulse generator will only be described in connection with agaseous discharge lamp.

As previously indicated, a ballast with a starting mechanism includedtherein, or otherwise a separate starting mechanism in combination withthe ballast, is often required for maintaining the light output of thefluorescent tube or similar gaseous discharge lamp. In this case, thepresent invention replaces the conventional ballast and/or startingmechanism with the impulse generator A. The impulse generator Agenerally includes a pair of input terminals 24 which are capable ofbeing connected to a suitable source of electrical current, as forexample, 110-volt alternating electrical current. The terminals 24 areconnected to opposite sides of a diode rectifier bridge 26 includingfour diodes 28 in the arrangement as illustrated in FIG. 1 of thedrawings. The bridge rectifier allows the impulse generator to be usedwith essentially any frequency signal since the input signal will berectified into a DC signal and this DC signal can be transmitted to thecollector of a transistor, as hereinafter described.

Connected across the two conductors 30 and 32 from the diode bridge 26is a capacitor 34 which operates as a ripple filter and is designed tofilter ripples from the signal in order to provide an essentially DCpure signal.

The diode rectifier bridge 26, along with the other components of theimpulse generator, allow the impulse generator to be used with eitheralternating electrical current or direct current. Moreover, the impulsegenerator can be operated with essentially any voltage and frequencylevels. Thus, for example, the source of current may be from theelectrical system of a mobile apparatus, such as an automobile, airplaneor the like.

The conductor 32 is also connected to a resistive capacitive network 36comprised of a resistor 38 and a capacitor 40, the latter of which isconnected to the base of an NPN transistor 42, in the manner asillustrated in FIG. 1 of the drawings. In like manner, the base of thetransistor 42 is similarly connected to the conductor 30 through anotherresistor 44. The resistor 38 and the capacitor 40 also operate incombination as a current limiting device, namely to keep the currentlevel within a range capable of being handled by the transistor 42.Thus, the resistor 38 should have a sufficiently high resistivity inorder to eliminate transients from being applied to the base of thetransistor 42. The capacitor 40 also prevents alternating current frompassing into the DC portion of the circuit and similarly furnishes adrive to the base of the transistor 42. It can be observed that as thevoltage changes, the base drive to the transistor would also change. Theresistor 44 controls the voltage drop across the transistor 42 andpermits bias on the base to start the transistor 42.

A primary coil 46 is connected across the conductor 30 and the collectorof the transistor 42 and, in this case, is often referred to as a"collector transformer coil". In like manner, an additional primarycoil, often referred to as an "emitter coil", or "emitter feedbackcoil", 48 is connected to the emitter of the transistor 42 and to theresistive capacitive network 36, in the manner as illustrated in FIG. 1of the drawings. In essence, the emitter coil is really a continuationof the collector coil and the two coils 46 and 48 could have been shownas one continuous coil with taps on the coil connected to the collectorand emitter of the transistor 42.

The primary coil 46 operates in conjunction with three secondary coils50, 54 and 56 which have terminals connected to the opposite terminalson the lamps L₁ and L₂. In this respect, it can be observed that anynumber of secondary coils may be employed, depending on the number oflamps which are to be energized by the circuit. Thus, if only one lampwere required, two secondary coils would be employed in order to furnishpulses to the opposite terminals of the lamp. The number of lamps andthe size of the lamps is, of course, limited by the circuit, and thecircuit can be designed with larger component values in order toaccommodate larger sizes or a larger number of lamps.

One of the terminals of the lamp, as for example the lamp L₁, isconnected through a conductor 58 to the terminal of the primary coil 46in common with the conductor 30. In the case of two lamps, one of theterminals of the lamp L₂ is connected through a conductor 60 to a tap onthe primary coil 46. In this case, a capacitor 62 would be located inthe conductor 60. While DC current may exist in the conductor 58, itcannot pass through the lamp by virtue of the capacitor 62. Moreover, byvirtue of this construction, the lower terminal of the lower bulb willhave a ground potential. Thus, a potential gradient exists between thetwo bulbs as shown.

The timing of the circuit is such that pulses are applied to theterminals of the lamp at a proper interval to maintain energization andrelatively constant light output. Thus, the pulses are generated in asequence and in a proper time interval so that they cause ignition andmaintain energization of the lamp so that there is no termination of anelectrical discharge in the lamp. Thus, in other words, pulses areapplied to the terminals of the lamp to turn the lamp on and maintainenergization of the lamp with a source of power across the terminals ofthe lamp, so that considerable power savings is achieved. The timing ofthe pulses is determined by the inductive capacitance and resistance andthe voltage of the output pulses. By varying the capacitance in thetiming circuit, it is possible to increase the efficiency of the device.In this respect, a variable capacitor could be substituted. Thefrequency of strobing the lamp with these output pulses is significantlyhigh so that it is not visible to the normal eye. Moreover, in view ofthe fact that there is no iron core, as in the classical ballast, thereis no generation of hum from the impulse generator.

The frequency of strobing the lamp is sufficiently high so that it isbeyond the audible range and also does not create any radio frequencyinterference. The maximum frequency should be about 50 kilohertz and theminimum frequency should be about 2 kilohertz, although as indicatedabove the frequency is voltage dependent.

The emitter coil 48 provides a feedback through the resistive capacitivenetwork 36 to the collector coil 46. It should also be observed that thesecondary coils 50, 54 and 56 are relatively small with respect to thecathode coil 46, and usually include only a few turns. Moreover, it canbe observed that with the circuit of the present invention it ispossible to both ignite the lamps L₁ and L₂ and to provide an energysource at high frequency from the same transformer coils. Thus, thecathodes are energized to ignite the lamp from the same source thatdrives the lamp.

In the case of one lamp, it is desirable to also use a capacitor, suchas the capacitor 62, in the conductor 60 in order to limit the currentapplied to one of the terminals of the lamp L₂. A positive potential isapplied to the collector of the transistor since the collector coil isof low resistance. The resistor 44 has a relatively high resistivity andprovides a bias on the base, thereby causing the emitter to becomenegative with respect to the collector. In this way, current will flowthrough the emitter coil and since the emitter coil is coupled to thecollector coil, pulses are generated at a time frequency established bythe resistive capacitive network 36. The pulse amplitude will increaseas the frequency increases and the frequency increases as the voltageincreases, as indicated above.

It can be observed in accordance with the above construction that theimpulse generator of the present invention operates somewhat as anoscillating circuit, although it does not oscillate on an AM or FM mode.Actually, the circuit oscillates on a pulse mode. The pulses are timedsuch that the lamp phosphors receive energy at certain intervals so thatexcitation of the gas in the lamp does not die out.

The device of the present invention also differs significantly from theconventional reactor transformer in the conventional ballast in thatcurrent is limited by the action of the voltage dependent frequencycharacteristics. This provides regulation to inhibit the in-rush ofcurrent as the lamps ignite which causes the high impedance level todrop almost toward a zero level. Thus, the device of the presentinvention provides almost the same output of light intensity as theconventional unit, but with significantly less energy. Moreover, thelamp is ignited in a manner to increase the overall life of the lamp.This results from the fact that the thrust of the pulses to the cathodeis much less than by the conventional ballast. The power factor of theimpulse generator is almost unity which is an advantage in manyapplications, particularly for utilities and the like.

FIGS. 4A and 4B illustrate the input and output wave forms.Particularly, FIG. 4A illustrates a sinusoidal voltage wave formdesignated as 70 with current pulses in the input wave form occurring atthe peaks in the amplitude in the voltage wave form. The output pulsesare more fully illustrated in FIG. 4B, and it can be observed that forthe direction and polarity of the output pulse as shown, the outputpulse generally has a rather gradual fall time from the leading edge tothe trailing edge for the greater portion of the pulse width. Thus, thepulse width is designated by reference numeral 74 and it can be observedthat about 7/8 of the pulse width includes the gradual fall at theleading edge and with a rather sharp rise time to generate a peak 76 oneach of the pulses. Thereafter, it can be observed that the fall time ineach of the pulses is quite rapid at the trailing edge. Moreover, byreference to FIG. 4B, it can be observed that there is a time lagbetween the next positive polarity pulse, (not shown) and designated byreference numeral 78. This time lag may be occupied by a negativepolarity pulse as measured from the trailing edge of one positivepolarity pulse to the leading edge of the next positive polarity pulse.

The circuit creates the slight "bend" in the trailing portion of thepulse and also only provides a very small peak so that it leads into therapid fall time. The voltage is somewhat gradual and hyperbolic for 90%of the time period in the waveform and wave direction as shown in FIG.4B. In this way, lamp life is increased significantly.

If the portion of the waveform between positive polarity pulses, e.g.,the portions designated by reference numeral 78 were occupied by anegative polarity pulses of a size and shape similar to the polaritypulses, then at least one the polarity positive pulses, the lamps wouldbe energized by pulses having an initially sharp rise time followed by agradual fall time and which fall time occupies the greater portion ofthe pulse width. Further the tail end of each of the pulses have afairly sharp decay, as in the waveform in FIG. 4B. This is an importantfactor in the present invention in that where the voltage and currentwaveform have pulses with a relatively sharp rise time and a relativelygradual fall time in the manner as shown, the power applied to the lampis such that the lamp is energized in a frequency of pulses and at powerlevels designed to maintain energization of the lamp with minimum energyrequirements. The current and voltage waveforms are designed so thatenergy is applied to the lamp to maintain energization of the same withthe pulses as shown in FIG. 4B such that the lamps are ignited with arelatively high power source and followed by a gradual decay which issufficient to maintain energization of the lamps. While the exact theoryof power savings is not understood as described herein, it is believedthat there is a relation between the current pulses and voltage pulses,with the waveforms shown in FIG. 4B, which enable the power savings tobe achieved with the same light output as compared to conventionalphosphor energizable lamps powered with conventional ballasts.

The transformer coils 46 and 48, along with the secondary coils 50, 54and 56, are preferably wound in a core transformer 80 of the typeillustrated in FIG. 5 of the drawings. Core transformers, andparticularly ferrite core transformers, are highly desirable for highfrequency operation. In this case, the core transformer 80 generallycomprises a cylindrically shaped central spool 82 upon which the coilsare wound. The spool 82 is formed of an electrically non-conductivematerial such as a plastic material. The spool 82 has a hollow center 84and accommodates inwardly intending tabs 86 on each of a pair of opposedhousing sections 88 and 90. By reference to FIG. 6, it can be observedthat the housing sections 88 and 90 are generally cylindrical in shapeand have an outer end wall 92 along with a peripherally extendingannular side wall 94. When in the assembled relationship, it can beobserved that the inner edges 96 of each of the side walls 94 are spacedfrom each other to form a gap 98 and, in like manner, the inwardlyextending projections 86 are spaced apart from each other in order toform a gap 100. The gap 100 has the same size as the gap 98. A spacer101 of electrically non-conductive material, e.g. a cardboard material,may also be located in the gap 100.

In the preferred aspect of the present invention, the distance betweenthe two housing sections which forms the gap should be about 3/16". Ifthe gap is too small, then energy savings are decreased, and if the gapis too large, then it will have a tendency to burn-out the transistor.

The housing sections are designed so that they generally enclose themagnetic lines of force in the housing configuration. One of the uniqueaspects of the present invention is that the typical core transformer isnot designed to be used with a gap between the housing sections.However, Applicant has found that it materially enhances the overallefficiency and effectiveness of the pulse generator by employing a gapbetween the two housing sections.

FIG. 8 illustrates another form of transformer which may be used withthe present invention and includes a spool 102 similar to the previouslydescribed spool 82. Again, the various coils are wound on the spool 102in the same manner as previously described. However, in this embodimentof the transformer, the housing sections 88 and 90 are eliminated and acentral core 104 formed of an electrically conductive material, such asan iron core, is inserted in the spool. This form of transformer hasalso been found to be effective in retaining the magnetic lines offorce.

The transformer acts as a type of auto-transformer in that all of thecoils are wound on the same spool. Thus, the secondary coils may bewound over the primary coil. Relative to a 120-volt input, the collectorcoil may have about 300 volts potential thereacross and the emitter coilmay have about a 100-volt potential thereacross. Due to the size of thesecondary coils, they will each have about a 3 to 4-volt potentialthereacross.

The device of the present invention has been tested and found to provideconsiderable power savings. Thus, in most cases at least a 34% percentreduction in power is obtained to maintain the same light output.Moreover, the impulse generator is relatively cool after many hours ofuse whereas a conventional ballast is too hot to be held in the humanhand.

Thus, there has been illustrated and described a unique and novelimpulse generator for use with phosphor energizable lamps and whichfulfills all of the objects and advantages sought therefor. It should beunderstood that many changes, modifications, variations and other usesand applications will become apparent to those skilled in the art afterconsidering this disclosure and the accompanying drawings. Therefore,any and all such changes, modifications, variations, and other uses andapplications which do not depart from the spirit and scope of theinvention are deemed to be covered by the invention which is limitedonly by the following claims.

Having thus described my invention, what I desire to claim and secure byLetters Patent is:
 1. A generator for use with a phosphor excitablelamp, said generator comprising:(a) input means to receive electricalcurrent, (b) means operatively connected to said input means forconducting said electrical current, (c) a pulse generating meanscomprising:(1) a solid state switching element connected to receive theelectrical current, (2) a primary inductive coil means connected to atleast one terminal of said switching element, (d) secondary coil meanslocated to be coupled with said primary coil means, and developing avoltage therein substantially less than in the primary coil means, (e)terminal means on said secondary coil means for connection to a phosphorexcitable lamp, (f) a first electrical current carrying conductorconnected to one end of said primary coil means and being adapted forelectrical connection to one terminal of said phosphor excitable lamp,and (g) an intermediate tap on said primary coil means, (h) a secondelectrical current carrying conductor connected to said intermediate tapon said primary coil means and being adapted for electrical connectionto another terminal of said phosphor excitable lamp, (i) a capacitivemeans in said second electrical current carrying conductor, (j) saidpulse generating means generating pulses in a sequence and at intervalssufficient to maintain energization of said lamp, said pulses beinggenerated with relatively high peak rise on the leading edge of saidpulses and a relatively gradual decay from said high peak for a greaterportion of the pulse width of each of said pulses but which decayreaches a relatively sharp fall to a zero level at the trailing edge ofsaid pulses, such that the pulses are designed to maintain ignition andenergization of the lamp with comparative current and voltage waveformsto achieve a power savings, and which pulses are transmitted from saidprimary coil means to said lamp through coupling of said lamp to saidprimary coil means.
 2. The generator of claim 1 further characterized inthat said solid-state switching element is a transistor and saidgenerator comprises pulse control timing means having aresistive-capacitive network.
 3. The generator of claim 2 furthercharacterized in that said primary coil means is connected to thecollector of said transistor, said resistive-capacitive network isconnected to the base of said transistor and an additional coil means isconnected to the emitter of said transistor.
 4. The generator of claim 1further characterized in that the pulses which are generated with therelatively high peak rise on the leading edge of the pulses and arelatively gradual decay from said high peak for a greater portion ofthe pulse width but which decay reaches a relatively sharp fall to azero level at the trailing edge of the pulses are current pulses.
 5. Thegenerator of claim 2 further characterized in that said primary andsecondary coil means form part of a core transformer.
 6. The generatorof claim 5 further characterized in that said core transformer comprisesa central sleeve with said primary and secondary coil means wound onsaid central sleeve, a pair of electrically conductive housing sectionsdisposed over said sleeve and coil means to substantially enclose saidcoil means and sleeve, said housing sections being spaced apart fromeach other by a gap.
 7. The generator of claim 5 further characterizedin that said core transformer comprises an electrically nonconductivesleeve with said coil means wound upon said sleeve, and an electricallyconductive metallic core disposed within said sleeve.
 8. The generatorof claim 2 further characterized in that said phosphor excitable lampcomprises a gaseous discharge lamp or an electroluminescent lamp.
 9. Agenerator for igniting a phosphor excitable lamp and controllingelectrical power applied to said phosphor excitable lamp, said generatorcomprising:(a) means for receiving an electrical current, (b) pulsegenerating means connected to said last-named means for generatingpulses of a magnitude to ignite and maintain energization of a phosphorexcitable lamp, said pulse generating means comrising a first inductivemember with a pair of end terminals and an intermediate tap thereon, anda solid-state circuit switching element connected to said inductivemember, (c) pulse control means operatively connected to said pulsegenerating means for enabling the pulses to be applied in a sequence andat a proper interval to said lamp to cause ignition of the lamp andmaintain energization of the lamp so that there is no termination of anelectric discharge in said lamp, said pulse generating means beingdesigned to enable said pulses to be generated with a relatively highpeak rise on the leading edges of said pulses and a relatively gradualdecay from said high peak for a greater portion of the pulse width ofeach of said pulses but which decay reaches a relatively sharp fall to azero level at the trailing edges of said pulses, such that the pulsesare designed to maintain energization of the lamp with comparativecurrent and voltage waveforms to achieve a power savings, and (d)conductive means for connecting said pulse generating means to aphosphor excitable lamp, said conductive means comprising:(1) a pair ofcurrent carrying conductors with one connected to one end terminal andthe other connected to the intermediate tap on said first inductivemember and adapted for connection to said phosphor excitable lamp, and(2) a secondary inductive member electromagnetically coupled to saidfirst inductive member and adapted for connection to said phosphorexcitable lamp, and (3) a capacitive means in said other of said currentcarrying conductors.
 10. The generator of claim 9 further characterizedin that said pulse generating means generates pulses having an amplitudeof short rise time and long fall time.
 11. The generator of claim 10further characterized in that the generated pulses are generated at atime corresponding to current pulses in the electrical current receivedby the generating means.
 12. The generator of claim 9 furthercharacterized in that the pulses which are generated with the relativelyhigh peak rise on the leading edge of the pulses and a relativelygradual decay from said high peak for a greater portion of the pulsewidth but which decay reaches a relatively sharp fall to a zero level atthe trailing edge of the pulses are current pulses.
 13. The generator ofclaim 9 further characterized in that:(a) said first inductive member isa primary coil connected to one terminal of said switching element, and(b) said solid-state switching element connected to said primary coil.(c) said means for connecting comprises terminal means on said primarycoil.
 14. The generator of claim 13 further characterized in that saidsolid-state switching element is a transistor and said pulse controlmeans comprises a resistive-capacitive network.
 15. The generator ofclaim 14 further characterized in that said first inductive member is aprimary coil, and said primary coil is connected to the collector ofsaid transistor, said resistive-capacitive network is connected to thebase of said trasistor and an additional coil is connected to theemitter of said transistor.
 16. The generator of claim 14 furthercharacterized in that one of said pair of conductors connects saidprimary coil to a conductive terminal on said lamp, and the other of theconductors connects the primary coil to an opposite conductive terminalon said lamp.
 17. The generator of claim 14 further characterized inthat said primary and secondary coils form part of a core transformer.18. A gaseous discharge lamp system comprising:(a) a gaseous dischargelamp comprised of(1) an enclosed bulb, (2) an electrically energizableelement associated wit said bulb, (3) at least a pair of terminalsassociated with said bulb, at least one of said terminals beingconnected to said electrically energizable element, and(4) an excitablephosphor in said lamp, (b) a generator operatively connected to saidlamp and being comprised of:(1) pulse generating means for generatingpulses of a magnitude sufficient to ignite said gaseous discharge lamp,said pulse generating means comprised of at least an inductive coilhaving a pair of end terminals, (2) a first electrical current carryingconductor connected to one end terminal on said inductive coil and beingadapted for electrical connection to one terminal of said gaseousdischarge lamp, (3) an intermediate tap on said inductive coil, (4) asecond electrical current carrying conductor connected to saidintermediate tap on said inductive coil and being adapted for electricalconnection to another terminal of said gaseous discharge lamp, (5) acapacitive means in said second electrical current carrying conductor,and (6) pulse control means connected to the means for generating pulsesfor controlling the generation of pulses in a sequence and at a properinterval to maintain ignition and energization of said lamp so thatthere is no termination of an electric discharge in said lamp, saidpulse control means operating with said pulse generating means to enablesaid pulses to be generated with a relatively high peak rise on theleading edges of said pulses and a relatively gradual decay from saidhigh peak for a greater portion of the pulse width of each of saidpulses but which decay reaches a relatively sharp fall to a zero levelat the trailing edges of such pulses, such that the pulses are generatedand applied to said lamp to maintain energization of the lamp withcomparative current and voltage waveforms to achieve a power savngs. 19.The system of claim 18 further characterized in that the pulses whichare generated with the relatively high peak rise on the leading edge ofthe pulses and a relatively gradual decay from said high peak for agreater portion to the pulse width but which decay reaches a relativelysharp fall to a zero level at the trailing edge of the pulses arecurrent pulses.
 20. The system of claim 18 further characterized in thatsaid means for generating pulses includes a solid-state circuitswitching element connected to one terminal of said inductive coil. 21.The system of claim 18 further characterized in that said pulse controlmeans generates pulses in a sequence and at a proper interval to causeignition of the lamp prior to the termination of an electric dischargein said lamp.
 22. The system of claim 18 further characterized in thatsaid pulse generating means generates pulses having an amplitude ofshort rise time and a relatively long fall time.
 23. The system of claim22 further characterized in that the pulse generating means generatespulses at a time corresponding to current pulses in the electricalcurrent.
 24. A generator for use with a phosphor excitable lamp, saidgenerator comprising:(a) input means to receive electrical current, (b)means operatively connected to said input means for conducting saidelectrical current, (c) a solid-state switching element connected toreceive the electrical current, (d) primary coil means connected to atleast one terminal of said switching element such that said primary coilmeans and switching element form a means for generating electricalpulses to be applied to said lamp for maintaining energization of same,(e) first and second terminals on said primary coil means and anintermediate tap on said primary coil means for connection to a gaseousdischarge lamp, (f) pulse control means operatively connected to saidswitching element for enabling the generation of pulses of relativelyfast increases in amplitude with a relatively fast time peak amplituderise at their leading edges and which peak amplitude falls rapidly afterenergization of said lamp and gradually for a substantial portion of thepulse width, said pulses occurring in a sequence and at intervalssufficient to maintain energization of said lamp, (g) a first electricalcurrent carrying conductor connected to a first terminal on said primarycoil means and being adapted for electrical connection to one terminalof said phosphor excitable lamp, (h) a second electrical currentcarrying conductor connected to said intermediate tap on said primarycoil means and being adapted for electrical connection to anotherterminal of said phosphor excitable lamp, and which pulses aretransmitted from said primary coil means to said lamp through couplingwith said first and second current carrying conductors such that thepulses maintain energization of the lamp with comparative voltage andcurrent waveforms to achieve a power savings, and (i) a capacitive meansin said second electrical current carrying conductor.
 25. The generatorof claim 24 further characterized in that said solid-state switchingelement is a transistor and said pulse control timing means is aresistive-capacitive network.
 26. The generator of claim 25 furthercharacterized in that said primary coil means is connected to thecollector of said transistor, said resistive-capacitive network isconnected to the base of said transistor and an additional coil means isconnected to the emitter of said transistor.
 27. The generator of claim25 further characterized in that a secondary coil means is located to beelectromagnetically coupled to said primary coil means with a voltagebeing developed in said secondary coil means which is substantially lessthan said primary coil means, said primary and secondary coil means formpart of a core transformer.
 28. A method of igniting and controllingcurrent flow to a phosphor excitable lamp, said method comprising:(a)receiving an electrical current, (b) generating pulses in an inductivemember having a pair of end terminals and an intermediate tap inresponse to said electrical current and which pulses are of a magnitudesufficient to at least ignite and maintain energization of a phosphorexcitable lamp, (c) controlling the generation of said pulses so thatthe pulses are generated with a relatively high peak rise on the leadingedges of said pulses and a relatively gradual decay from said high peakfor a greater portion of the pulse width of each of said pulses butwhich decay reaches a relatively sharp fall to a zero level at thetrailing edges such that the pulses are designed to maintainenergization of the lamp with comparative current and voltage waveformsto achieve a power savings, (d) delivering the pulses from the inductivemember through one current carrying conductor connected to one endterminal of said inductive member and to at least one terminal of saidlamp and through a second current carrying conductor having a capacitortherein and connected to the intermediate tap on said inductive memberand another terminal of said lamp to cause ignition of and maintainenergization of said lamp.
 29. The method of claim 28 furthercharacterized in that the received electrical current is an alternatingcurrent, and said method comprises rectifying said current.
 30. Themethod of claim 28 further characterized in that the method comprisesgenerating the pulses with an amplitude of short rise time and long falltime.
 31. The method of claim 28 further characterized in that thepulses which are generated with the relatively high peak rise on theleading edge of the pulses and a relatively gradual decay from said highpeak for a greater portion of the pulse width but which decay reaches arelatively sharp fall to a zero level at the trailing edge of the pulsesare current pulses.
 32. A generator for use with a gaseous dischargelamp, said generator comprising:(a) input terminals to receiveelectrical current, (b) rectifying circuit means operatively connectedto said input terminals to receive said electrical current forrectifying said electrical current, (c) a transistor connected toreceive the rectified current, (d) a primary coil connected to at leastone terminal of said transister, (e) a secondary coil located to beelectromagnetically coupled with said primary coil, and developing avoltage substantially less than that in the primary coil, (f) a feedbackloop containing a feedback coil connected across a second terminal and athird terminal of said transister, (g) a resistive-capacitive circuitportion in said feedback loop such that a current is generated in and avoltage is generated across said primary coil which is sufficient tomaintain energization of a gaseous discharge lamp with substantiallyreduced power requirements, at least said current having a relativelyfast high peak rise on its leading edges and with a more gradual decaywhich reaches a zero level at the trailing edges, (h) terminal means onsaid secondary coil for connection to a gaseous discharge lamp, (i)first and second terminals and an intermediate tap on said primary coilfor connection to a gaseous discharge lamp, (j) a first electricalcurrent carrying conductor connected to the first terminal on saidprimary coil and being adapted for electrical connection to one terminalof said gaseous discharge lamp, (k) a second electrical current carryingconductor connected to the intermediate tap on said primary coil meansand being adapted for electrical connection to another terminal of saidgaseous discharge lamp, and (l) a capacitive means in the secondelectrical current carrying conductor.
 33. The generator of claim 32further characterized in that said primary coil is connected to thecollector of said transistor, said resistive-capacitive network isconnected to the base of said transistor and said feedback coil isconnected to the emitter of said transistor.
 34. The impulse generatorof claim 32 further characterized in that an electrical conductor alsoconnects the terminal means on said primary coil to a conductiveterminal on said lamp.
 35. The generator of claim 32 furthercharacterized in that said primary and secondary coils form part of acore transformer.
 36. The generator of claim 32 further characterized inthat a resistor is connected between said rectifying circuit means andsaid third terminal of said transistor to at least control voltage dropacross said transistor.
 37. The generator of claim 32 furthercharacterized in that certain of said foregoing components comprisepulse control timing means for generating pulses in a sequence and atintervals sufficient to maintain energization of said lamp.
 38. Thegenerator of claim 32 further characterized in that the pulses which aregenerated with the relatively high peak rise on the leading edge of thepulses and a relatively gradual decay from said high peak for a greaterportion of the pulse width but which decay reaches a relatively sharpfall to a zero level at the trailing edge of the pulses are currentpulses.
 39. A generator for use with a phosphor excitable lamp, saidgenerator comprising:(a) means to receive electrical current, (b) meansoperatively connected to said means to receive current for conductingsaid electrical current, (c) transistor connected to receive theelectrical current, (d) a core transformer comprised of:(1) a centralsleeve, (2) a primary coil means wound on said central sleeve, (3) asecondary coil means wound on said central sleeve, and (4) a pair ofelectrically conductive housing sections disposed over said sleeve andcoil means to substantially enclose said coil means and sleeve, saidhousing sections being spaced apart from each other by a gap, saidprimary coil means being connected to at least one terminal of saidtransistor such that said primary coil means and transistor form a meansfor generating electrical pulses to be applied to said lamp formaintaining energization of same, said secondary coil means located tobe electromagnetically coupled with said primary coil means, (e)terminal means on said primary coil means for connection to a gaseousdischarge lamp, and (f) pulse control timing means comprised of aresistive capacitive network operatively connected to said transistorfor causing the generation of pulses of relatively fast increases inamplitude with a relatively fast time peak amplitude rise at theirleading edges and which peak amplitude falls rapidly after energizationof said lamp and then gradually for a substantial portion of the pulsewidth, said pulses occurring in a sequence and at intervals sufficientto maintain energization of said lamp, and which pulses are transmittedto said primary coil means and said lamp through coupling with saidprimary coil means such that the pulses maintain energization of thelamp with cooperative voltage and current waveforms to achieve a powersavings.
 40. The generator of claim 39 further characterized in thatsaid primary coil means is connected to the collector of saidtransistor, said resistive-capacitive network is connected to the baseof said transistor and an additional coil means is connected to theemitter of said transistor.
 41. The impulse generator of claim 40further characterized in that an electrical conductor also connects saidprimary coil means to a conductive terminal on said lamp.
 42. Agenerator for use with a phosphor excitable lamp said generatorcomprising:(a) input means to receive electrical current, (b) meansoperatively connected to said input means for conducting said electricalcurrent, (c) a pulse generating means comprising at least a transistorconnected to receive the electrical current, (d) a core transformercomprised of:(1) a primary coil means, said primary coil means beingconnected to one terminal of said transistor, (2) a secondary coil meanslocated to be coupled with said primary coil means, (3) a central sleevehaving said primary coil means and secondary coil means wound thereon,and (4) a pair of electrically conductive housing sections disposed oversaid sleeve and said first and second coil means to substantiallyenclose said first and second coil means and said sleeve, said housingsections being spaced apart from each other by a gap, (e) terminal meanson said secondary coil means for connection to a gaseous discharge lamp,and (f) a pulse control timing means having a resistive-capacitivenetwork for controlling timing of the pulses, said pulse generatingmeans generating pulses in a sequence and at intervals sufficient tomaintain energization of said lamp, said pulses being generated withrelatively high peak rise on the leading edge of said pulses and arelatively gradual decay from said high peak for a greater portion ofthe pulse width of each of said pulses but which decay reaches arelatively sharp fall to a zero level at the trailing edge of saidpulses, such that the pulses are designed to maintain ignition andenergization of the lamp with comparative current and voltage waveformsto achieve a power savings, and which pulses are transmitted from saidprimary coil means to said lamp through coupling of said lamp to saidprimary coil means.